Industrial process control environments typically require physical sensing of parameters such as temperature, pressure, flow rate, strain, displacement, humidity, vibration, etc. Adapting a sensor network and its cabling infrastructure to existing plant environments is usually cost prohibitive.
Various sensors that incorporate transmitters are known in the art. For example, U.S. Pat. No. 5,774,048 (incorporated herein by reference) relates to a valve that generates a wireless transmittable signal if pressure drops within vehicle tires. U.S. Pat. No. 6,005,480 to Banzhof et al. relates to similar subject matter.
U.S. Pat. No. 6,199,575 to Widner (incorporated herein by reference) discloses a valve system that includes a MEMS pressure sensor that senses pressure and functions as a mechanical actuator for a valve. A transmitter is integrated with the valve and a receiver is located at a remote location. A transmitter may be formed on the MEMS along With a pressure transducer and its associated circuitry. An alternative embodiment is disclosed in which a digital modulator is included in a transducer valve.
U.S. Pat. No. 6,445,969 to Kenney et al. (incorporated herein by reference) discloses a system and method of monitoring process parameters associated with a manufacturing or testing process. This reference discloses that radio frequency identification tags may be used to transmit an event signal. If an event trigger is detected, a command is sent to a particular sensor to measure a specified process parameter.
U.S. Pat. No. 6,484,080 to Breed discloses an acceleration sensor including an RFID unit. U.S. Pat. No. 6,563,417 to Shaw discloses an RFID tag including a temperature sensor.
Pneumatic or fluid controlled valves are known in the art and used in a variety of applications, such as to control water and other fluids in nuclear reactors. Such valves are discussed in U.S. Pat. No. 5,197,328 to Fitzgerald; U.S. Pat. No. 6,026,352 to Burns et al.; U.S. Pat. No. 5,329,956 to Marriott et al.; and U.S. Pat. No. 5,774,048 to Achterholt, all of which are incorporated by reference. In a typical pneumatic operated valve, a current to pressure (I/P) transducer is coupled to a valve positioner which supplies an operating pneumatic pressure to a valve diaphragm actuator. The diaphragm actuator in turn is coupled to a sliding valve stem and plug. Feedback is provided by a mechanical linkage, such as by a valve positioner arm having one end connected to the actuator/valve stem and the other end coupled to the positioner so as to track movement of the valve stem. Alternatively, electrical signal feedback is provided from installed valve positioner instrumentation.
The value of sensor for providing both diagnostics and prognostics is readily accepted; however, innovative technical developments are needed to facilitate the implementation.